Process of producing potassium nitrate.



H. BLUMENBERQ, JR. PROCESS 0F Pnouucmc POHSSIUM mums.

APPLiCATiON FiLiD SAN 2, Hi8.

Patented Mar. 4, 1919.

I 3 WW4. m? z a M 4 a UNITED STATES PATENT OFFICE.

HENRY BLUMENLMRG, JR, 0]? LOS ANGELES, CALIFORNIA.

PROCESS OF PRODUCING POTASSIUM NITBATE.

Application filed January 2, 1918.

To all Hf/10m it may concern:

Be it known that I, HENRY BLUMENBERG, J12, a citizen of the UnitedStates, residing at lios Angeles, in the county of Los Angclcs and Stateof California, have invented new and useful Improvements in Processes ofProducing Potassium Nitrate, of which the following is a specification.

My invention relates to a process of producing potassium nitrate, directfrom the waste gases of cement kilns, or any gases carrying potassiumsalts or oxids in sus' pension.

As well known, the great demand for potassimn salts and the limitedsupply at the present time have turned the endeavors of inventors tosources of potassium supply which, until lately have not been.considered as commercial propositions. It has been proposed to usepotassium containing materials in the manufacture of hydraulic cement.The potassium is volatilized as K 0 and carried with the flue gaseswhich in addition to the products of combustion carry considerableamount of cement dust. An apparatus is provided for recovering thepotassium. carried in these flue gases, but considerable difficulty hasbeen experienced in devising a process or an apparatus for efficientlyand economically recovering the mtassium. v

It is an object of this invention to devise a simple yet eiiicientprocess of recovering the potassium from the waste gases of rement kilnsand the like which as stated above occurs usually in the form of K 0. Myprocess is based on the fact that potassium bases have an intenseafiinity for nitrogen oxids replacing the weaker bases. It is well knownthat practically all the metal nitrates are decomposed at a temperatureof red heat. liberating the nitrogen oxids. but the affinity ofpotassium for nitrogen oxid is so intense that a white heat requiredbefore decomposition takes place, and consequently potassium nitrate ispractically the only salt containing nitrogen mus which must be heatedbeyond the dis association temperature of nitrogen oxid before thedecomposition takes place.

My invention consists of the steps in the lil'oce'ss hmeinafterdescribed and claimed.

I n the accompanying drawings which form a part of this specification, Ihave illustrated by way of example, an apparatus suitable 1' or carryingout my process.

Specification of Letters Patent.

Patented Mar. 4, 1919.

Serial No. 209,978.

In the drawings, 10 designates a portion of a cement kiln which is hereshown to be of a rotary cylindrical ty e. 11 indicates a suitableapparatus whereiiy the raw material is fed into the stack end of thecement kiln 10. The waste gases enter the lower end of a stack or chimne12, which, how ever, is only used when or any reason the potassiumnitrate recovering apparatus hereinafter described is not in operation.13 is a lid or damper normally closing the stack 12. H is a conduit forconveying the Waste gases into a precipitating chamber or tower 15. 16is a slide-valve whereby the conduit 14 may be closed. The tower 15 hasan exit 17 at the top. A series of baflle platis 18, which are hereshown arranged in staggered relation, but which may be of any preferredconstruction, is provided in the interior of the tower 15. 19 is a tankfrom which, by means of a pump 20, a liquid may be pumped through pipe21 to the top of the towel 15 and there sprayed by means of a nozzle 22.The liquid is retarded in its downward assage by the baflie plates 18 inthe wellnown. manner, thereby allowing the same to become intimatelymixed with the waste ases coming from the cement kiln 10. he liquidcollecting at the bottom of the tower 15 is returned, by means of pipe23, to the tank 19 which latter is provided with a valved outlet pipe 24whence the liquid may be conveyed to an evaporating pan 2a, which, bymeans of a valved pipe 26 and pump 27, is connected to a filter press 28for separating the liquid from the solid constituents.

In the operation of my process, I prepare a solution of sodium nitratein the tank 19 and circulate the same by means of the pump 20 throughthe precipitating tower 15. The sodium nitrate solution will on contactwith the waste gases carrying potassium oxids, potassium silicates andcarbon dioxid form sodium carbonate, hydrosilieates, aluminum hydroxid,and potassium nitrate. Only a small quantity of aluminum hydroxid, notexceeding one to two per cent. is formed. The same is derived from thealuminum silicates carried in the waste gases. The followimc equationexplains the reaction:

The equation just given is representative of the reaction taking place.It should be remembered, however, that there are other potassiumcompounds such as potassium silicates or potassium sulfate present inthe waste gases which Will react with the metal nitrate to formpotassium nitrate. Potassium sulfate is present in rather largequantities when in lace of powdered coal, a fuel oil is used, w ichnormally carries a very large percenta e of sulfur compounds.

As explaine above, the potassium being the stronger base will displacethe sodium from the sodium nitrate and form potassium nitrate. In myprocess the gas tension is broken down because of the chemical afiinityof the carbon dioxid for the sodium salts and the alkaline constituentsof the cement dust. As cement dust carries large quantities of calciumoxid, calcium carbonate is formed. At suitable intervals the magma orslurry in the tank 19 is drawn ofi" into the evaporating pan 25 wherethe slurry is heated to render the gelatinous silicates insoluble. HotWater is now added to the mass and the same is pumped through the filterpress 28, thereby separating the soluble salts, sodium carbonate andotassium nitrate from the insoluble constituents of the mass. The sodiumcarbonate is separated from the potassium nitrate by the usual methodsof crystallization. The potassium nitrate, as well known, forms an idealfertilizer because of its potassium and nitrogen contents.

I have described the above process of producing potassium nitrate fromgases carrying potassium salts or potassium oxid in suspension by thetreatment with sodium nitrate. My invention however, is applicable toother metal nitrates, such as the alkaline earth nitrate and alkalimetal nitrates. In fact any metal nitrate for instance, lead nitrate,may be used in place of sodium nitrate, but for commercial reasonssodium nitrate would be used under normal commercial conditions.

Various changes in the steps of'the process may be made withoutdeparting from the spirit of my invention as claimed.

I claim:

1. A process of recovering potassium salts from gases containingpotassium compounds in suspension, comprising 'contactin said ases witha metal nitrate solution, tiereby orming potassium nitrate, andseparating the potassium nitrate from the mixture.

2. A process of recovering potassium salts from gases, containingpotassium compounds, comprising contacting said gases with a sodiumnitrate solution, thereby.

forming potassium nitrate, and separating.

potassium nitrate from the mixture. u

3. The process of recovering potassmm salts from ases, containingpotassiun'1gc0m pounds an cement dust in suspension and carbon dioxid,comprising contactingflsaul ases with a metal nitrate solution, thettlity orming potassium nitrate and separating the potassium nitrate fromthe mixture.

4. A process of recovering potassium salts from gases containingpotassium compounds and cement dust in suspension, and carbon dioxid,comprising contacting said gases with a sodium nitrate solution, therebyforming potassium nitrate and sodium car bonate and hydrosilicates,evaporating to dryness to render the silicates insoluble, mixing withwater and separating the po- -tassium nitrate from the mixture.

In testimony whereof I have signed my name to this specificat on.

HENRY BLUMENBERG, JR.

